Gear-teeth



With es'ses:

P. WAGNER.

GEAR TEETH. APPLICATIUN FILED NOV- 21.: 1914.

Pafeted Aug; 15,1916.

F. WAGNER.

femmina. l IAPPLICATIONFIL'IED NOV. 27| 1914t 1,194,904. 1 Patented Aug. 15,1916.

n -z SHEETS-SHEET 2.

Fig. 6..

Wl'tnesss A Invent or Paul Wagner.,

His DTttorneg.

UNITED sTATEs PATENT orricii..

Y-PAUL OF CHARLOTTENBURG, GERMANY, ASSIGNOR TOGENERAL ELECTRIC Y y p Y t COMPANY, uA`CORPORA'IION 0Fv NEW YORK.

GEAn-TEETH.

To all ich-01m, it lmay conce/Mi.:

Be it known that I, PAUL IVAGNER, a subiect of the King of Prussia,Mresiding atv Charlottenburg, Germany, have invented certain new and vuseful Improvements in Gear-Teeth, of which the following is a little or no rubbing action. Gear wheels` specification: f

This invention relates to ltoothed gear wheels, `and its object` is to provide intermeshing gear teeth which-will operate with are customarily constructed with involute Aor cycloidal teethIt said teeth meet in a plane intersectingl or parallel ,with the axes of rotation of they wheels, there will be ifarring and wear, unless the length of the v Kath otengagement ot any two engaging teeth is greater than the pitch. The ordinary rule, therefore, is to make the height ot 'the addendum or'fpart above the pitch line' equ'aLto three-tenths of the pitch., and the dedendum or part belownthe pitch line equal to' four-tenths of the pitch. Such teeth are objectionable,fhowever, because the speciiic load they can'transmit is low;

first. by reason of 4the bending strains on` the face of the teeth, a'nd second, because the. faces of the teeth notonly roll one upon th'e other (particularly toward the beginning sliding or rubbing action of the faces oi"in' volute and cycloidal gears, respectively; and Fig. 6 shows a modified form of involute teeth.

Referring first-to Fig. l, the pitch circles for` the spur gear and pinion respectively are indicated at 1 and 2. The' customary form of involute teeth is shown by the dotand it willbe observed that when ted lines, I

the direction `of the arthe wheels rotate in row, the path `of engagement between any begins at the point two intermeshing teeth A ll. In other words,

3 and ends at the point be it extends for a distance equal to 'about twice Speciicatioii ofLet-ters Patent.

Application led November 27, 1914. Serial No. 874,101.

the pitch of the teeth, as indicated by the center lines 'of the teeth. The line 6-6 of this path of lenga-gement is taken at an angle of 15 degrees to the tangent of the segment, as is customary in gears of this type. -In Fig. 4 the black sections show those portions of involute teeth Awhich slide upon each other as the teeth pass along their path ot engagement. Y

In Fig. Q there are shown in dotted lines a spur gear andv pinion having the customary` cycloidal teeth', tlie'generating circles being indicated at 7 and 8. The curved path of engagement lies between the points 9 and- 10, and its length is substantially twice the pitch. Fig. '5 shows'by the black sections the portions which rub upon each other'as the teeth pass alo-ng the line 9-10.

Itis evident yth at in respect to the possible specific pressure upon the teeth and the wear of their faces by friction a considerable improvement may be obtained if the mutual -sliding can be wholly or nearly avoided.

This result becomes possible it the actual engagement of the teeth takes place only at or near the point where the pitch circles touch each other; or, in other words, it the path ot engagement is shortened to. less than the pitch. Such a construction is `feasible if a helical twistedor herringbone arrange- -ment of the teeth is adopted. Fig. 3' shows a herringbone design ofthe teeth.- The continuous intermeshing of wheels of this type is attained it, regarding any aXials'ection, at least the extent of one axial division,- as indicated at 11, remains continually in-engagement. Since Fig. 3y shows 'tenfpoints in engagement, this condition isv amply ful-.

filled. During the movement of the teeth inl the direction ot the arrow 12, the individual points of engagement.` 11 of any two meshing teeth move axially from the lone'lend to the other end of the teeth. This movement, which is the ordinary vmovement of helical teeth in mesh, is, in eiiect, a rolling movement in a directionparallel to the aXis of the wheel. With the double helical or herringbone 'type of' gear as shown, in which the .wheel comprises `two sections provided with teeth which are oppositely inclined, this movement isfrom the center of the wheel toward the outside on each half.

As has been stated, it is possible with a herringbone design to limit the. extent ot engagement in a peripheral direction tothe close vicinity'- of." the point where .the pitchv circles-are tangent, and this fact makes it possible to avoid almost'entirely anyusliding of the faces of the teeth, one upon the4 other, if the teeth are given the forms indicated by theheavy lines'in Figs. 1 and Between the dotted .lines 15, 16 on either I side of the pitch circles in Fig. l, the origi,

nal outline of the involuteI teeth ispreserved.'

'Inside and outsidevoffthis area the faces of teeth are considerably cut back asA 1 compared 'tov the 'that they do not at the new original conguration, s0 any timecome'in co tact. Thus the'path of engagement for this type of teeth is reduced from 3-4 to 17` 17 which is less than one-half the pitch. Similarly, in Fig. 2,*the path of engagement for the new cycloidal teeth is reduced from 9 10 to 18-'18, which is4 also less' than one-half the pitch. Under these circumstances, the

- length of the teeth can be greatly shortened,

preferably to about one-half the pitch.'

Compared with the customary type kof increase in the cause it is made l it'is not necessary to' make the path of en, gagement ofthe involute 'teeth in- Fig. 1` tangential 'to the point where the p'itch cir-' cles touch.

of the pitch circles, while `fo1f""1*` ig. l ltheyE are inclined to the radius; With^the form of vtooth shown lin Eig. -6, the radialcomponent of the tooth ists in Fig. 1, disappearsf The faces; of the teeth' in .Figl 6- arel cut -back ,with relation to the rollingcurve 19 on bothsides of the point of contactof the pitch circle, so that material fromv which theyteeth are the: radial depth o teeth,'the new form permits a considerable.'

' pressure on their faces, be# at single points. Moreover,

If, therefore, as shown in 'Fig 6,-. lthe two circles are regarded'a's rolling to-, gether, then the rolling curvesa19 'are radialin the direct vicinity of the point 'of Contact;v

the tangential line oi? engagement becomes l a point, vgeometricall'y regarded. In rea1ity",.

it will become'al short line beforesand after the point of contact of account of'. the elastic compression of.4 the made. `With` this short'pa-th of engagementjandthe cutting 'back of the teeth, they only ,roll on each other without sliding, and thus the' wear due to friction is avoidedI f 1 patent statutes, I have described the prin?` .ciple `(if/operation with .the"apparatus' WhClI 110W consider to represent'the best embodiment thereof;

the pitch circles,v one s* Inaccordance with the 'provisions of the of my. invention, together l but I desire to have-it understood that v.the 'A apparatus shown'- isl only illustrative and that the invention canbe carried 'out by other-means'. What I claim as new and desire to secure by Letters Patent of 1. v A gear' wheel of the herringbone `f whose 'teeth is about one-- half the pitch. 'y 4 2.I Gearjwheels of -the helical type whose path, ofengagement in a'plane of -tionisgless than one-half the pitch.

3.. Ina gearing, 'the combination of. meshin'gjgear.wheelsof-the helical type, the raigagementiin ,afpl'a'ne v4offreyolution is less aio the United States,-is:-P type,`

revolu-V l l dlaldepthvof Whose-teeth l1s about one-halfl aying vtheirv faces cut inyjhandthisZrd day of October, 1914. j :"frAUL WAGNER. 'vll'itnessesz'4 v l' GnsTAv HLBROGK, MANFRED Rnrr. 

